Methods for qualitative and quantitative determination of ethanol in aqueous body fluids, particularly human body fluids, are used in medicine and in law enforcement.
In medicine, determination of ethanol in blood is significant in diagnosing liver malfunction and alcoholism. In law enforcement, such assays are used to determine whether an automobile operator is or is not driving under the influence of alcohol.
East German Patent Publication DD 256,196 Al discloses a test strip for determining ethanol content in biological fluids. The test strip is based on the following series of chemical reactions: ##STR1## wherein MTT is [3-(4,5-dimethylthiazolyl-2) 2,5-diphenyltetrazolium].
The test strip contains:
(1) a compound which is suitable for electron transfer such as 1-methoxy-phenazine methosulfate; PA1 (2) a tetrazolium salt, in particular MTT[3 -(4,5-Dimethyl(thiazolyl-2)2,5-diphenyl tetrazolium], and/or INT[2-(4-iodophenyl)- 3-(4-nitrophenyl)-5-diphenyl tetrazolium]; PA1 (3) an alcohol dehydrogenase (ADH); PA1 (4) a nicotinamide adenine dinucleotide (NAD.sup.+); and PA1 (5) a buffer (pH 1-4), in particular a glycine/hydrochloric acid buffer and a buffer (pH of 7-9), in particular semicarbazide buffer. PA1 Poly(acrylamide-co-2-acrylamido-2-methylpropane sulfonic acid, sodium salt). The preferred polymer coverage is 0.6 g/m.sup.2. A useful range is about 0.1 to 4 g/m.sup.2):
The problem is that this element is not suitable for a quantitative assay of ethanol after a 1 to 2 weeks of storage at room temperature. Incorporation of the above chemicals into a dry multilayer element designed for quantitative assays of ethanol consistently underpredicts ethanol concentrations after only three weeks of keeping. In addition, the above prior art element is subject to interference from components of blood serum such as ascorbic acid.